933. Number of Recent Calls LeetCode Solution

In this guide, you will get 933. Number of Recent Calls LeetCode Solution with the best time and space complexity. The solution to Number of Recent Calls problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Table of Contents

1. Problem Statement
2. Complexity Analysis
3. Number of Recent Calls solution in C++
4. Number of Recent Calls solution in Java
5. Number of Recent Calls solution in Python
6. Additional Resources

Problem Statement of Number of Recent Calls

You have a RecentCounter class which counts the number of recent requests within a certain time frame.
Implement the RecentCounter class:

RecentCounter() Initializes the counter with zero recent requests.
int ping(int t) Adds a new request at time t, where t represents some time in milliseconds, and returns the number of requests that has happened in the past 3000 milliseconds (including the new request). Specifically, return the number of requests that have happened in the inclusive range [t – 3000, t].

It is guaranteed that every call to ping uses a strictly larger value of t than the previous call.

Example 1:

Input
[“RecentCounter”, “ping”, “ping”, “ping”, “ping”]
[[], [1], [100], [3001], [3002]]
Output
[null, 1, 2, 3, 3]

Explanation
RecentCounter recentCounter = new RecentCounter();
recentCounter.ping(1); // requests = [1], range is [-2999,1], return 1
recentCounter.ping(100); // requests = [1, 100], range is [-2900,100], return 2
recentCounter.ping(3001); // requests = [1, 100, 3001], range is [1,3001], return 3
recentCounter.ping(3002); // requests = [1, 100, 3001, 3002], range is [2,3002], return 3

Constraints:

1 <= t <= 109
Each test case will call ping with strictly increasing values of t.
At most 104 calls will be made to ping.

Complexity Analysis

• Time Complexity: O(3000) = O(1)
• Space Complexity: O(3000) = O(1)

933. Number of Recent Calls LeetCode Solution in C++

class RecentCounter {
 public:
  int ping(int t) {
    q.push(t);
    while (q.front() < t - 3000)
      q.pop();
    return q.size();
  }

 private:
  queue<int> q;
};
/* code provided by PROGIEZ */

933. Number of Recent Calls LeetCode Solution in Java

class RecentCounter {
  public int ping(int t) {
    q.offer(t);
    while (q.peek() < t - 3000)
      q.poll();
    return q.size();
  }

  private Queue<Integer> q = new LinkedList<>();
}
// code provided by PROGIEZ

933. Number of Recent Calls LeetCode Solution in Python

class RecentCounter:
  def __init__(self):
    self.q = collections.deque()

  def ping(self, t: int) -> int:
    self.q.append(t)
    while self.q[0] < t - 3000:
      self.q.popleft()
    return len(self.q)
 # code by PROGIEZ

Additional Resources

• Explore all LeetCode problem solutions at Progiez here
• Explore all problems on LeetCode website here

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